FIG. 8 is a perspective view of a conventional optical reflection element. Optical reflection element 1 has inner frame 5, a pair of meandering-shaped first vibration elements 4 and 8, outer frame 2, a pair of meandering-shaped second vibration elements 6 and 7, and mirror 9. Second vibration elements 6 and 7 have their outer ends supported by respectively confronting portions of an inside of outer frame 2. Second vibration elements 6 and 7 support inner frame 5 with their inner ends. First vibration elements 4 and 8 have their respective outer ends supported by confronting portions, which are orthogonal to vibration axis S12 of the first vibration elements, along an inside of inner frame 5. First vibration elements 4 and 8 have vibration axis S11. First vibration elements 4 and 8 support mirror 9 with their inner ends.
In optical reflection element 1, mirror 9 and inner frame 5 function as mass bodies. These mass bodies vibrate under the effects of torsional vibrations and oscillations of any of second vibration elements 6 and 7 and first vibration elements 4 and 8.
Optical reflection element 1 of such structure causes inner frame 5 and mirror 9 to swing with large amplitude when it resonates with turbulent vibrations or it receives impacts from the outside. First vibration elements 4 and 8 deform, and they even become damaged when the deformation exceeds their permissible level as a result of these vibrations. There are thus such cases that optical reflection element 1 become damaged when it receives turbulent vibrations or impacts from the outside.
There are a number of techniques that are aimed at suppressing amplitude of vibrations in at least one of directions of X-axis and Y-axis and/or a direction of Z-axis in order to reduce damages to optical reflection element 1, such as one disclosed in Patent Literature 1. To be specific, outer frame 2 and inner frame 5 are provided with asperities formed on them to suppress impacts in any of the directions of X-axis and Y-axis. A unitary structure provided with such impact suppression measures can be achieved easily by altering a mask design used for producing the optical reflection element. It is difficult, however, to take similar measures against the direction of Z-axis, and an additional impact suppressing member, or a protector for instance, is disposed to suppress the amplitude of vibrations in the direction of Z-axis.
Problems arise, however, when a protector is provided to suppress the amplitude of vibrations in the direction of Z-axis, such that it results in increase in number of components and the task of keeping accuracy of alignment during the assembling. In addition, the protector needs to be disposed in a location away from first vibration elements 4 and 8 and second vibration elements 6 and 7, since first vibration elements 4 and 8 and second vibration elements 6 and 7 vibrate in operation. It is this reason that makes downsizing difficult, and leaving the optical reflection element less resistible against large impacts.